/Engine/Plugins/Online/OnlineSubsystemUtils/Source/OnlineSubsystemUtils/Public/VoiceInterfaceImpl.h
Checks that a unique player id is on the specified user's mute list
true if the specified user is muted, false otherwise
virtual bool IsMuted ( uint32 LocalUserNum, const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & UniqueId ) const